Time Again For Biosolids?

John Matel

By John Matel

Next year, we will thin 110 acres of loblolly pine planted in 2003. This is a little bit early, but it looks like they will be ready before the usual time. I have been trying to figure out what made trees on this land grow better. What conditions were present and/or what did I do that I could do again.

The difference in this stand was that we applied biosolids in 2008, i.e. at year five for the loblolly.

My research indicated that loblolly could benefit from fertilization after they were in the ground around five years, since before that time there was enough fertility in the soil as a result of decomposition of slash from the last harvest. Fertilization in year five or six “feeds” the trees at least for the next five or six years and encourages canopy close.

I was interested in biosolids because of their organic nature, and the fact that they release nutrients gradually as they decompose. I was also interested in something that would build my soil. Like most piedmont tree farms, the soil on mine was abused by more than a century of growing tobacco and corn. During those times, much of the topsoil washed into the rivers and streams. That is why these lands are growing trees today, and not crops. Biosolids have bulk that contributes to soil mass. So beyond providing the necessary phosphorus, nitrogen and potassium, biosolids also provide many micronutrients.

I wanted to grow more wood, but trees are more than wood and forests are more than trees. A healthy forest is the top of my list of goals. This means land the grows wood, while providing wildlife habitat, natural beauty AND protection for soil and water. That last one – water – was something I worried about. I was not going to apply any type of fertilizer that would negatively impact the water that crossed my land. So I did some reading and studying and attended workshops sponsored by Virginia Tech. The studies indicated no significant impact on water when biosolids were properly applied. Not only could our stream management zones take care of runoff, our growing trees and forbs and grasses under them, the stuff the wildlife likes, didn’t even let much get away.

Remember when I talked about piedmont soils being impoverished by centuries of farming? They are now deficient in many of the basic nutrients that favor the growth of forests, forbs and flowers. The natural communities growing on the land are hungry enough to take up all that the biosolids can reasonable give them.

So, I am an advocate for the use of biosolids in forestry in Virginia. Do I have any concerns? Of course, like anything else, we need to apply biosolids appropriately, being careful to exceed best management standards to protect our soil and water. My research also indicates that it might not be a great idea to apply biosolids to my longleaf groves. This is not the problem of biosolids, but of fertilizers in general. Loblolly responds very well to fertilization. Longleaf does well on weaker soils. A problem of longleaf restoration in Virginia is that loblolly outcompetes longleaf. We do not need to tip this balance any more in favor of loblolly, but this is a tangential issue. We are generally growing more loblolly than longleaf.

My complaint is that I cannot seem to get more biosolids in Brunswick County. My forestry management is not intense, so I do not need biosolids every year. I would like to apply biosolids about six years after planting and again after first thinning about ten years later. As I wrote above, I am planning to thin the 110 acres where we applied biosolids in 2008. I would also like to apply biosolids to forty-five acres I thinned in 2017 and to around eighty-five acres we will thin early in 2018. In both cases, we thinned/will thin to a basal area of 50, so there is plenty of room for equipment.

My trees are still living off the boost they got in 2008. Time for another meal.

(John Matel is a landowner and sustainable tree farmer in Brunswick County. He wrote an original blog post on his use of biosolids in 2008, which can be found below.)

2008 Blog Post:

A Forest and Field Day – With Biosolids

One of the great services provided by the State of Virginia is ongoing landowner education. The courses I like are usually hosted by Virginia Tech and I prefer to go to the Southern Piedmont Research Station near Blackstone, VA because that is close to my forest land. Forestry is very localized in terms of soils and climates. I prefer to share the experience with people who work with my kind of tree in similar climates and soil types.

Below is a discussion of precommercial thinning. The Dept of Forestry recommends it to keep the forests healthy. I already did mine.

I attended a field day that included talks on forest road maintenance, carbon credits & pond management, as well as a tour of a local saw mill.

The instructors and my fellow landowners are always very nice to me, but I am strange to them with my northern accent and unusual background. Most of the other landowners are old south & rural and I feel always in the presence of Andy Griffith or Billy-Bob Thorton. They inherited their land, which has often been in their families for many generations.

As the older generation dies off, farms and timberlands are left to kids who have moved away to the cities. They often divide it up among the heirs and sell it off. This leads to fragmentation of the forests. 100 acres in one parcel is not the same as 100 acres divided in to ten or twenty fragments. You really cannot practice forestry on land less than forty acres. We also talked about conservation easements, which might reduce this trend. A conservation easement lowers taxes in return for a contract never to develop the land. It stays in forest or farm. This can be a good thing.

I also went down to my forest to check on the biosolids application. The workers had just finished. There is a little smell to the biosolids, but not that much. The bigger effect is that the heavy machinery crushes down the vegetation, including some of my trees. It would be better to apply biosolids first and then do pre-commercial thinning. There is not that much damage really. The rows are far apart and unless the trees are actually run over by the tires there is a good chance they will recover.

My forest is looking very good in terms of spacing and tree health. There is a debate re how close the trees should be. The closer spacing provides more wood at first, but lower quality. The closely spaced trees are also more stressed and in more danger from insects. Wildlife also does better with more widely spaced trees. Anyway, my choice is more spacing. I am interested to see how much fertilization does for the trees. Most forest owners do not fertilize at this stage and I am one of the first in the area to use biosolids at this stage of the lifecycle. Virginia Tech has studied the applications of biosolids in Southside Virginia. I went to their seminar last year and I trust them, so I am doing what they recommend. We did 132 acres of the 2004 generation. I probably should have left a control plot for comparison.

Below are what the biosolids look like. These particular pellets produced by anaerobic digestion. Some are lime stabilized and in more liquid form. Biosolids are a great circle of life thing – from flush to farm. Wastes are applied to land to produce more growth and life. Virginia Tech has found no significant amount gets into the water supply, even when applied massively beyond what we usually do. People complain about the smell, but I walked all over the place and hardly noticed them. It is a mild fertilizer smell that will go away in a couple of weeks. BTW – this was the place where they piled them for spreading. The actual spread is much thinner.

One side benefit of the application was the paths the machines made through the brambles. I was able to get to places on the land where I never set foot before. In fact, I was so beguiled by the new paths that I stayed too long and almost didn’t get back home in time.

Below is a sweet gum in its fall colors. They are pretty trees, but sort of like big weeds if you are trying to grow pine. This one is near the stream managment zone and it is a natural part of the Virginia landscape, so we will let it to grow to old age and I will enjoy its color next fall too. It will be prettier each year.

Quick Facts

What other options do municipalities have for managing biosolids?

Other options include disposal in sludge incinerators and co-disposal with trash in landfills. Learn more.